Our principal interest during the next year will be centered around the special features involved in the initiation of transcription of T4 DNA by purified RNA polymerase for the synthesis of five specific messenger RNAs, i.e. for alpha and beta glucosyltransferase, dCMP hydroxymethylase, deoxynucleotide kinase and dihydrofolate reductase. We will continue to explore the role of the different nucleotides on the initiation process and specifically the role of monovalent cations in the reaction. The size of the individual messengers will be determined by the technique of sucrose density gradient centrifugation. In the second part of the program we hope to determine the amino acid sequence of a tryptic peptide of 5000 MW that represents the binding site of glutamine in the enzyme, formylglycinamide ribonucleotide a midotransferase.